1. Field of the Invention
The present invention relates to the field of titaniferous ore beneficiation and, more particularly, to an improved method for removing iron from a titaniferous ore by high temperature chlorination.
2. The Prior Art
Beneficiation methods employing high temperature chlorination have been faced with the problem of eliminating the iron oxide component in a titaniferous ore without losing titanium values in the course of producing a low iron beneficiate. Iron in the beneficiate causes a disposal problem as well as loss of chlorine in subsequent use to produce TiCl.sub.4. Muskat, U.S. Pat. No. 2,184,884, sought to minimize titanium losses by restricting the reducing condition or using no reductant at all.
Fukushima, et al, U.S. Pat. No. 3,803,287 have employed low carbon and claimed a higher rate of reaction to attempt to accomplish this goal. A replacement beneficiate is made when iron values in the ore are replaced with TiO.sub.2. Beneficiation by "replacement" is much more rapid and produces a more desirable harder product useful for producing titanium tetrachloride. The "replacement" beneficiate does not abrade as easily as a removal beneficiate to form fines or dust with a concomitant loss of titanium values. Formation of a "replacement" product involves generation in situ of TiCl.sub.4 and its reaction with iron oxide, manganese oxide and magnesium oxide in the ore to deposit TiO.sub.2 and volatilize these ore components as chlorides. Since TiCl.sub.4, which is highly volatile, is being generated, there is a probability of its escape from the reaction zone. It is obvious that the rate of the replacement reaction controls whether any TiCl.sub.4 will escape causing a loss of titanium values. I have found that the rate of replacement is a function of the iron oxide concentration in the bed and chlorination of beneficiate at extremely low iron levels will produce increasing TiCl.sub.4 losses as lower iron levels are sought. Therefore, the problem exists of how to produce a low iron oxide containing titaniferous ore beneficiate without losing considerable quantities of titanium values. I have discovered a novel process for making such a product using staged reactors, one of which is smaller than the other.